Level 1-9: Directly under Green Pigs.
Level 1-20: In the bushes of the planet.
Level 2-13: In the bushes of the bottom planet.
Level 2-25: On the starting planet, opposite from the slingshot.
Level 2-28: In the snow, next to the arrow sign.

Tips for High Scores
Easy Three-Stars: Launching as few birds as possible to complete a stage increases score, getting you a three-star rank.

High Scores: Doing as much damage as possible in each level will also increase score.

Frozen Pigs: Pigs must be in a bubble when not within a planetoid's atmosphere. Instead they'll be in bubbles. Pop the bubbles and the pigs will freeze, then shatter.

Contruction Materials: Wood is weakest, then Ice, then Rock. Aim for Wood when possible.

Shooting Backwards: You don't always have to aim forward when you use the slingshot to launch birds. You can also aim backwards, and some stages actually require it.

Ice, Ice, Baby: Use the Ice Bird to turn Wood and Rock into Ice, then use the Blue Birds to easily shatter all of the created Ice.

Bird Types and Strategies

Red Bird: The Red Bird is your standard weapon bird. Doesn't have any special powers, but does do well against Wood.

Lazer (Purple) Bird: Just like the Kamikaze bird from the original Angry Birds, except you can tap anywhere on the screen to create a purple target, which the Lazer Bird will then aim at.

Bomb Bird: Simple launch this bird anywhere you want to do massive damage. Wait until after the bird has made impact, then tap the screen to make him explode, doing a ton of damage.

Blue Birds: Exactly the same as they are in the original Angry Birds, the Blue Birds split into three when you tap the screen, and are effective against Ice structures.

Terence: Terence is a giant green bird with extreme desctructive power. Launch him in the middle of any structure to easily topple it over.

Ice Bird: The Ice Bird is the newest addition to the Angry Birds fleet. Launching this bird into any Wood or Rock structures will freeze them, turning them into Ice. The Ice Bird should be used in conjunction with the Blue Birds in a strategy that has the Ice Bird turning everything into Ice, then the Blue Birds, which are strong against Ice, can smash everything to smithereens.

Space Eagle: The Space Eagle is a special bird that can only be used if you have tokens. You earn three tokens for free, then you can either earn more for defeating boss characters, or you can buy more tokens through in-app purchases.

You don't launch the Space Eagle. When you use a token, you launch a can of sardines. Whereever the sardines hit, it will create a black hole in that area. The Space Eagle will appear from the black hole, destroying everything in its path.